The objective of this program is to obtain in vitro measurements of the wall shear stress, wall pressure, and detailed intralumenal flow patterns produced by pulsatile flow through models of arterial bifurcations. Both the pulsatile flow waveforms and the model geometries will conform to conditions existing in the adult human aortoiliac and carotid bifurcations. The measurements, to be made with hot-film wall probes and special pressure transducers, will consist of low-frequency data (including low harmonics of the cyclic pulsatile frequency) as well as time-resolved power spectral densities of the higher harmonic components characteristic of disturbed and turbulent flow. A laser-induced fluorescence technique will be used to obtain spatially- and temporally-resolved flow patterns and velocities.